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Influence of in vitro test conditions on release of aspirin from commercial tablets.

The influence of in vitro test conditions on the release of aspirin from commercial tablets was assessed with a USP rotating-basket dissolution apparatus. Three types of aspirin tablets were evaluated: plain, buffered, and microencapsulated. The variables investigated were stirring speed, pH, and volume and temperature of the dissolution medium. Plain tablets gave the best dissolution profiles under all experimental conditions, except at pH 3. Microencapsulated tablets showed sustained release. For all three types of tablets, faster dissolution was observed at pH 4.5 compared with that in artificial gastric juices. Increasing the stirring rate increased the dissolution rate, an effect most pronounced for plain tablets. Very similar dissolution curves were obtained when the dissolution test was conducted in 500 and 900 mL of dissolution media regardless of the pH of the media. No significant difference in dissolution profiles was observed when the effect of temperature was investigated. The dissolution data were evaluated on the basis of theoretical dissolution equations and by linear transformation of dissolution curves. Highly significant linear correlation coefficients revealed that the cube root equation could be used to describe drug release in artificial gastric juices, regardless of tablet type. When pH 4.5 buffer solution was used as the dissolution medium, different kinetic models were applicable.

Aspirin↗

Programmable drug release of highly water-soluble pentoxifylline from dry-coated wax matrix tablets.

The programmable release of pentoxifylline from a dry-coated wax matrix tablet containing behenic acid as wax matrix was investigated at 37 degrees C in Japanese Pharmacopeia XII 1st (pH 1.2) and 2nd (pH 6.8) fluids. The dry-coated tablet consisted of a low drug concentration (33% w/w) in the outer layer tablet and a high concentration (50-67% w/w) in the core. The drug release from the wax matrix significantly increased after penetrating the core; therefore, the drug release profiles showed specific biphasic curves. Because the contact angle of the wax matrix tablet increased with a decrease in the drug concentration, the fluid penetration in wax matrix tablet increased with an increase of the drug concentration. The time required for 75% drug release (T75) decreased with an increasing drug concentration in the core, and the T75 at pH 6.8 was slightly longer than that in pH 1.2. The larger core tablet had a shorter T75, indicating that the drug release rate was controlled by regulating the drug concentration and/or the weight of the core tablet.

Chemical Phenomena↗

Evaluation of the antimalarial properties and standardization of tablets of Azadirachta indica (Meliaceae) in mice.

The antimalarial activities of the tablet suspension of the bark and leaf of Azadirachta indica were evaluated on Plasmodium yoelli nigeriensis infected mice. The tablet suspensions exhibited high prophylactic, mode-rate suppressive and a very minimal curative schizonticidal effect. No animal was cured of the infection in the curative test and there was not much increase in the survival time of the animals compared with the control. The tablet suspensions from the leaf and bark at a concentration of 800 mg/kg and chloroquine at a concentration of 62.5 mg/kg body weight produced average percentage (%) parasitaemia of 79.6%, 68.2% and 99.5% for leaf, bark and chloroquine, respectively, in chemosuppression. Also in the prophylactic treatment, the tablet suspensions at 800 mg/kg and pyrimethamine at a concentration of 0.35 mg/kg gave an average parasitaemia reduction of 75.3%, 65.6% and 98.3% for the leaf, bark and pyrimethamine, respectively. There was a clear indication that both tablet suspensions from the leaf and bark possess antimalarial activity and a suspension from the former is relatively more effective than the bark. Extrapolation of the results from the antimalarial activity of the tablet suspension of the crude plant parts showed that an adult human would need to ingest a minimum of 48 g of the powdered plant material per day, an amount that is impracticable. A survival index value of 0.33 was obtained with the 800 mg/kg dose level, indicating that the tablet suspension has some moderate beneficial effect.

Administration, Oral↗

Desorption electrospray ionization mass spectrometry: direct toxicological screening and analysis of illicit Ecstasy tablets.

Desorption electrospray ionization mass spectrometry (DESI-MS) was used as a simple and rapid way to analyze drug tablets and powders without sample preparation. Experiments were performed with a home-made DESI source coupled to a triple-quadrupole linear-ion trap (QqQ(LIT)) mass spectrometer. Twenty-one commercial drugs as well as some illicit Ecstasy tablets and powders were analyzed. MS spectra almost exclusively showed the protonated or deprotonated ion of the drug after directing the pneumatically assisted electrospray onto the tablet's surface. With some tablets, inhomogeneity of the surface resulted in different spectra depending on the spot analyzed, thus showing that DESI could be used for imaging. Directly triggered MS/MS spectra were used for confirmatory analysis, with analysis times often below 10 s per tablet. For illicit Ecstasy tablets, DESI-MS, GC/MS and LC/MS analyses provided similar qualitative results for the main analytes. With MS/MS spectra library comparison or exact mass measurements, this technique could become very powerful for the rapid analysis of unknown tablets and shows the great potential of desorption techniques as an alternative to solution-based analysis.

Drug Evaluation, Preclinical↗

Correlations between in vitro dissolution rate and bioavailability of alaproclate tablets.

In two different absorption studies, quantitative correlations between the in vitro dissolution rate and the bioavailability have been shown after single administration of various tablet compositions of alaproclate hydrochloride to healthy subjects. Both statistical moment analysis and the use of empirical single value parameters were tested. For conventional tablets a linear relationship was obtained between mean dissolution time in vitro and in vivo. A similar relationship was obtained between the mean dissolution time in vitro and the mean residence time for controlled release tablets of the matrix type. It was also possible to establish an in vitro--in vivo correlation for these latter tablets by using the single point estimate of maximum plasma concentration as in vivo parameter. When comparing the mean dissolution time in vitro to the total area under the plasma drug concentration-time curve attained after different types of tablets, it is obvious that the extent of bioavailability of alaproclate will not fall below 80% of the value found for an aqueous solution until the mean dissolution time in vitro exceeds approximately 3 hr. Statistical moment analysis seems to have a broader applicability than the use of empirical point estimates, and it seems to be useful both for conventionally dissolving tablets and controlled release tablets.

Absorption↗

Gastric emptying of indigestible tablets in relation to composition and time of ingestion of meals studied by metal detector.

Enteric-coated tablets leave the stomach mainly during the interdigestive phase. Composition as well as time of ingestion of meals may influence their gastric emptying considerably. In 12 normal volunteers gastric emptying of a plastic tablet with a metal core was followed by a metal detector in relation to different compositions and various times of ingestion of meals. With an empty stomach and after ingestion of 250 ml water, the mean time for gastric emptying of the tablet was 38 +/- 11 min (mean +/- SEM) and 38 +/- 8 min. Two hundred fifty milliliters of milk (652 kJ) and a formula diet (1000 kJ) delayed gastric emptying time to 128 +/- 14 and 152 +/- 6 min, respectively (P less than 0.05). Breakfast (2200 kJ) further retarded gastric emptying compared with both liquids to 249 +/- 24 min (P less than 0.05). There was a close correlation between nutritive density and gastric emptying of the tablet (r = 0.92; P less than 0.001). Main meals also delayed gastric emptying of tablets when compared to empty stomach (P less than 0.05). A snack after breakfast further delayed gastric emptying from 201 +/- 10 to 278 +/- 19 min (P less than 0.05). The largest delay was observed following ingestion of breakfast, lunch, dinner, and additional snacks (509 +/- 220 min). We conclude that the delay of gastric emptying of enteric-coated tablets by food is related to its nutritive density and eating habits. The gastric emptying of an enteric coated tablet that is ingested early in the morning may be delayed until late at night when several meals and snacks are ingested during the day, leading to unwanted alterations in bioavailability and to possible adverse effects.

Adult↗

Improvement by super disintegrants of the properties of tablets containing lactose, prepared by wet granulation.

The crushing strength, disintegration and dissolution properties of tablets, made by wet granulation with lactose as filter, gelatin as binder, potato starch as disintegrant and magnesium stearate as lubricant can be markedly improved when the potato starch (20%) is replaced by a much lower concentration (4%) of an insoluble super disintegrant, such as sodium starch glycolate (Primojel) or crospovidone (Polyplasdone XL). The incorporation of partially water soluble super disintegrants such as low-substituted sodium carboxymethylcellulose (Nymcel, ZSD 16), causing a viscous barrier in the tablets when containing water, is shown to be deleterious for both tablet disintegration and drug release. In contrast to potato starch, the position of the super disintegrants (intragranular, extragranular or equally distributed) had hardly any effect on the tablet properties. The improved properties of the tablets containing insoluble super disintegrants, when compared to tablets with potato starch, are the result of the use of a much lower concentration of disintegrant, but especially of the difference in effect of magnesium stearate on the disintegration capacity of the slightly swelling potato starch and the strongly swelling super disintegrants, respectively. The latter cause, even in the presence of the liquid penetration inhibiting hydrophobic magnesium stearate, a chain reaction of opening of the tablet, starting at the outside and resulting in a fast disintegration.

Excipients↗

Comparison between a new 13C-urea breath test, using a film-coated tablet, and the conventional 13C-urea breath test for the detection of Helicobacter pylori infection.

BACKGROUND: In Japan, urea breath-testing includes mouth rinsing with water immediately after the ingestion of (13)C-urea solution, to prevent false-positive results that are caused by oral bacteria with urease activity. Our objective was to evaluate the diagnostic performance of a urea breath test using a film-coated (13)C-urea tablet and omitting mouth rinsing. METHODS: The study was a multicenter trial comparing the solution- and tablet-based urea breath tests (UBTs). Helicobacter pylori status was determined by histology, culture, and rapid urease testing. RESULTS: Of the 255 subjects who completed the study, evaluation of the tablet-based UBT was possible in 254, and comparison of the tablet-based UBT and the solution-based UBT was possible in 250 patients. When the assessment achieved by a combination of biopsy-based methods was used as a reference standard, the sensitivity, specificity, and accuracy of the tablet-based method were determined to be 97.7%, 98.4%, and 98.0%, respectively. When the results of the solution-based UBT were used as a reference standard, the sensitivity, specificity, and accuracy of the tablet-based UBT were determined to be 96.9%, 97.6%, and 97.2%, respectively. CONCLUSIONS: The (13)C-urea tablet-based method proved to be a simple and accurate test for the diagnosis of H. Pylori infection. Mouth rinsing was not required.

Adult↗

Near-infrared methods for the identification of tablets in clinical trial supplies.

Near-infrared reflectance analysis (NIR) methods have been developed for the confirmation of the identity of blister-packed tablets for clinical trial supplies. Three approaches are described: (1) presentation of single exposed tablets from blisters directly to the optical window; (2) presentation of unopened opaque blister-packed tablets directly to the optical window of the NIR instrument; and (3) use of a fibre-optic accessory to examine tablets through unopened opaque blister packs. For clinical purposes, all tablets in this trial were manufactured to match the appearance of one another. Tablets containing four strengths of an experimental drug (2, 5, 10 and 20% w/w of the active), a marketed product as a clinical comparator (80% w/w of the active), and a placebo were investigated. The NIR methods were developed by chemometrically building a library with second derivative spectra for each tablet type. Library validation and test data are presented along with a comparison of the three sample presentation techniques. The scope and limitation of each sample presentation technique are discussed.

Clinical Trials as Topic↗

Temperature, pH and agitation rate as dissolution test discriminators of zofenopril calcium tablets.

Comparative in vitro dissolution studies were performed on several tablet batches of zofenopril calcium, an ACE inhibitor, to determine if they could be differentiated on the basis of their release rates. The samples included six batches produced at Site 1 and one batch produced at Site 2. Using regular dissolution conditions (USP paddle method at a 50-rpm agitation speed in phosphate buffer, pH 7.5, at 37 degrees C), release rates of all the tablet batches were similar. By independently altering one of the dissolution test parameters, either a lower pH or a slower agitation rate, discrimination between the Site 1 and Site 2 tablets was enhanced. Discrimination was only slightly enhanced when a lower dissolution medium temperature was used. Tablets made from different polymorphs of zofenopril calcium could not be differentiated by their dissolution profiles, even with the more discriminating conditions. The dissolution profiles of certain other zofenopril calcium tablets (including film-coated vs uncoated tablets, and tablets made with micronized vs unmicronized drug particles) were indistinguishable using a 50-rpm agitation rate, but they could be clearly differentiated using a 40-rpm agitation rate.

Captopril↗

Open-label, dose-ranging pilot study of 4 weeks of low-dose therapy with sodium phosphate tablets in chronically constipated adults.

BACKGROUND: The tablet formulation of sodium phosphate (NaP) is a prescription osmotic purgative that has been marketed since 2001. The use of NaP tablets in patients with constipation has not been studied previously. OBJECTIVE: This study assessed the tolerability and efficacy of 28 days of therapy with NaP tablets (1.5 g NaP/tablet) in patients with chronic constipation. METHODS: Adults with functional constipation or constipation-predominant irritable bowel syndrome and Z-3 spontaneous bowel movements (BMs) during the 7-day screening/baseline period were eligible for this open-label, dose-ranging study. Patients were randomized to receive starting doses of 4 NaP tablets (group A) or 8 NaP tablets (group B) each morning for 28 days. After a minimum of 48 hours, the NaP dose could be titrated upward (in the case of no BM or no relief of symptoms) or downward (in the case of a predefined excess laxative response) by 2 tablets/d to a minimum of 2 tablets/d or a maximum of 12 tablets/d. Patients kept a diary of their BMs and gastrointestinal symptoms. A serum chemistry panel was obtained weekly. The primary end points were the constipation response (based on the change from baseline in weekly number of BMs) and the global sense response (based on daily scores for the patient's overall sense of change in their bowel problems). RESULTS: At randomization, there were 18 patients in group A and 25 in group B. Of these, 40 patients (16 group A, 24 group B) had > or 7 days of diary information while taking study treatment and were evaluable for efficacy. The constipation response rate was 100% in group A and 95.8% in group B, and the respective global sense response rates were 68.8% and 79.2%. Four patients in group B withdrew due to adverse events, none of which were serious. Five patients had occasional hypokalemia that required no treatment. Changes from baseline in serum concentrations of calcium, inorganic phosphorus, and potassium were not clinically significant and did not require treatment. CONCLUSIONS: In this small study, NaP tablets taken daily were generally well tolerated (particularly in the low-dose group) and produced prompt relief of constipation--generally within the first week of treatment--that was sustained over the 28-day treatment period. A reasonable starting dose appears to be 2 to 4 tablets (3-6 g NaP) daily.

Adult↗

Two replicate randomized, double-blind, placebo-controlled trials of the time to onset of pain relief in the acute treatment of migraine with a fast-disintegrating/rapid-release formulation of sumatriptan tablets.

BACKGROUND: The gastric stasis that commonly accompanies migraine headache may impair absorption of conventional oral tablets in the stomach. A fast-disintegrating/rapid-release formulation of sumatriptan has been developed to enhance tablet disintegration and drug dispersion and potentially improve absorption. OBJECTIVE: Two studies were conducted comparing the time to onset of relief from moderate or severe migraine pain with the fast-disintegrating/rapid-release formulation of sumatriptan tablets 50 and 100 mg and placebo. METHODS: These were 2 identically designed randomized, double-blind, parallel-group studies. Sumatriptan 50 or 100 mg or placebo was taken on an outpatient basis to treat a single moderate or severe migraine attack. Using a personal digital assistant, patients recorded the time of dosing and the time at which pain severity reached none or mild (ie, pain relief) or none (ie, pain free) in real time so that the time to onset of relief could be measured as a continuous variable. Onset of relief was defined as the earliest time point at which a statistically significant difference in pain relief compared with placebo was achieved and maintained through 2 hours after dosing. Before dosing and at pre-determined time points after dosing, patients also provided an assessment of migraine pain as none, mild, moderate, or severe. At a clinic visit within 1 week after treatment of the migraine attack, patients were queried about adverse events. For each adverse event, investigators recorded whether study medication was considered the cause. Data analyses were undertaken for each study individually and, in post hoc analyses of the primary and key secondary end points, on pooled data from both studies. RESULTS: The 2 studies comprised 2696 patients: 902 received sumatriptan 50 mg, 902 received sumatriptan 100 mg, and 892 received placebo. Patients' mean age ranged from 40.2 to 40.8 years across treatment groups, and most patients were female (83%-87%) and white (92%-93%). In the analysis of pooled data, sumatriptan tablets provided significantly more effective pain relief compared with placebo as early as 20 minutes after dosing with the 100-mg dose and as early as 30 minutes after dosing with the 50-mg dose (P < or = 0.05). Similar results were observed for the individual studies: in study 1, sumatriptan tablets were significantly more effective than placebo at 25 minutes with the 100-mg dose and at 50 minutes with the 50-mg dose; in study 2, sumatriptan tablets were significantly more effective than placebo at 17 minutes for the 100-mg dose and at 30 minutes for the 50-mg dose (P < or = 0.05). In the pooled data, the cumulative percentages of patients with pain relief by 2 hours after dosing were 72% for the 100-mg dose and 67% for the 50-mg dose, compared with 42% for placebo (P < or = 0.001, both sumatriptan doses vs placebo). The cumulative percentages of patients with a pain-free response by 2 hours were 47% for the 100-mg dose, 40% for the 50-mg dose, and 15% for placebo (P < or = 0.001, both sumatriptan doses vs placebo). In the individual studies, significantly more patients receiving either sumatriptan dose were migraine free 2 hours after dosing and had sustained pain relief and a sustained pain-free response over 24 hours compared with placebo (P < or = 0.001, both sumatriptan doses vs placebo). The only drug-related adverse events reported in >2% of patients in any treatment group in either study were nausea (both studies: 3% sumatriptan 100 mg, 2% sumatriptan 50 mg, 1% placebo) and paresthesia (study 1: <1% sumatriptan 100 mg, <1% sumatriptan 50 mg, 0% placebo; study 2: 3% sumatriptan 100 mg, 1% sumatriptan 50 mg, <1% placebo). CONCLUSIONS: In these studies, sumatriptan tablets in a fast-disintegrating/rapid-release formulation were effective for the acute treatment of moderate to severe migraine pain, were generally well tolerated, and achieved an onset of pain relief as early as 20 minutes for 100 mg and as early as 30 minutes for 50 mg.

Adult↗

Effects of food on the single-dose pharmacokinetics/pharmacodynamics of tizanidine capsules and tablets in healthy volunteers.

BACKGROUND: A multiparticulate capsule formulation of the alpha2-adrenergic agonist tizanidine has been developed to decrease C(max), AUC, and associated somnolence, while maintaining efficacy. OBJECTIVE: The purpose of this study was to compare the pharmacokinetics and impact of somnolence on cognitive function after single doses of the tablet and capsule formulations of tizanidine under fed and fasted conditions in healthy volunteers. METHODS: This Phase I, single-dose, randomized, open-label, 4-way crossover study was conducted at MDS Pharma Services, Belfast, United Kingdom. Healthy male and female adult subjects received tizanidine (8 mg) as tablets and capsules under fasting and nonfasting conditions. Blood samples were collected to determine plasma tizanidine pharmacokinetic profiles, and computerized cognitive function tests were performed that yielded a validated composite score, Power of Attention, an index of sedation. RESULTS: Ninety-six patients were enrolled in the study (54 men, 42 women; mean [SD] age, 27 [8] years [range, 18-52 years]; mean [SD] body weight, 71.7 [12.4] kg [range, 46-102 kg]). Tizanidine tablets and capsules were found to be bioequivalent after fasting. In the fed state, mean C(max) and AUC(0-t) were substantially decreased, by 33.8% and 15.4%, comparing the capsules and tablets, respectively. The median T(max) increased significantly from 1.41 to 3.0 hours (P < 0.001). Administration of the capsules with food resulted in <20% difference in mean C(max) and AUC(0-t) compared with the fasting state, whereas mean C(max) and AUC(0-t) were 22.6% and 45.2% higher when the tablet formulation was administered with food. The onset of impairment in Power of Attention was significantly delayed from 0.75 to 1.5 hours postdose when capsules were administered with food compared with the other conditions (P < 0.001). The most commonly reported adverse events were asthenia, somnolence, and orthostatic hypotension. A significantly lower adverse event rate was observed in the combined capsules group compared with the tablets, suggesting that differences in tolerability may exist. CONCLUSIONS: The results of this study in healthy volunteers suggest that the capsule and tablet formulations of tizanidine were bioequivalent only in the fasted state. The capsule formulation exhibited a food effect that reduced C(max) and AUC(0-t), and significantly increased T(max), which was associated with a delay in cognitive impairment. The large interpatient variability in plasma profiles most likely dampened the ability to fully elucidate the differences between the 2 formulations.

Adolescent↗

Preparation of monolithic osmotic pump system by coating the indented core tablet.

A method for the preparation of monolithic osmotic pump tablet was obtained by coating the indented core tablet compressed by the punch with a needle. Atenolol was used as the model drug, sodium chloride as osmotic agent and polyethylene oxide as suspending agent. Ethyl cellulose was employed as semipermeable membrane containing polyethylene glycol 400 as plasticizer for controlling membrane permeability. The formulation of atenolol osmotic pump tablet was optimized by orthogonal design and evaluated by similarity factor (f2). The optimal formulation was evaluated in various release media and agitation rates. Indentation size of core tablet hardly affected drug release in the range of (1.00-1.14) mm. The optimal osmotic tablet was found to be able to deliver atenolol at an approximately constant rate up to 24h, independent of both release media and agitation rate. The method that is simplified by coating the indented core tablet with the elimination of laser drilling may be promising in the field of the preparation of osmotic pump tablet.

Adrenergic beta-Antagonists↗

Cefdinir: A comparative study of anhydrous vs. monohydrate form. Microstructure and tabletting behaviour.

Anhydrous cefdinir (AC) vs. monohydrated cefdinir (MHC) was compared in order to be used as antimicrobial in therapeutics. Different techniques have been used to characterize physically AC and MHC, and also a complete microstructural analysis of raw materials was carried out. Cefdinir and Maltodextrin QDM 500 (3:2) formulations were compressed in order to obtain tablets with typical dose of Cefdinir, i.e. 300 mg. Dissolution profiles were obtained for both AC and MHC tablets. Finally tablet X-ray diffraction was performed to ensure the stability of the monohydrated form after tabletting being clearly different in both AC and MHC crystals. AC crystal structure was agreed with the known pattern of anhydrous Cefdinir described in the literature. Microstructural analysis showed large differences in specific surface area (SSA), confirmed by mercury intrusion. Crystal structures of both AC and MHC were stable under mixing, compression and storing processes. Dissolution profiles were faster for hydrate form, probably related to microstructural properties of the crystal which remained after tabletting. In conclusion, it is possible to isolate Cefdinir in two forms anhydrous and monohydrate, well characterized and differentiated. The use of this later improves dissolution of tablet dosage form due to the lack of interconversion during tablet manufacture.

Anti-Infective Agents↗

Efficacy of a new ketoconazole bioadhesive vaginal tablet on Candida albicans.

To develop more effective treatment for vaginal candidasis, ketoconazole (KTZ) was formulated in bioadhesive tablet formulations that increase the time of contact of drug with the vaginal mucosa. The bioadhesive vaginal tablets delivery of KTZ was prepared by direct compression of sodium carboxymethyl cellulose or polyvinylpyrrolidone or hydroxypropylmethyl cellulose (HPMC-E(50)). Dissolution studies of bioadhesive tablets and commercial ovules were carried out with a new basket method (horizontal rotating basket). In vitro, a good sustained release action was obtained with bioadhesive tablets containing 1:1 and 1:2 drug/polymer ratio using HPMC-E(50). These bioadhesive tablets containing 400 mg of KTZ showed a zero-order drug release kinetic. KTZ solutions at increasing concentrations (0.16, 0.33, 0.5 and 0.66 mg/ml) were prepared for microbiological trials. These concentrations correspond to 25%, 50%, 75% and 100% of KTZ released from bioadhesive tablets, respectively. Yeast mixture was mixed with each concentration of KTZ at ratio of 1:10. One hundred microliters of this mixture was transferred in 900 microl liquid Sabouraud medium after a certain time interval for each concentration of KTZ and incubation at 37 degrees C for 24 h. Then this culture streaked onto Sabouraud-dextrose-agar plates, which were incubated at 37 degrees C for 48 h. The 0.16 and 0.33 mg/ml concentrations of KTZ showed fungistatic effect in 120 min. The 0.5 mg/ml concentration of KTZ was fungistatic in 90 and 120 min; and the 0.66 mg/ml concentration of the drug was fungistatic in 120 min as well as in 180 min. It was found that, in vitro antifungal activity of KTZ was dependent on its concentration and contact time with yeast cells. These results indicated that a new bioadhesive vaginal tablet formulations might be further developed for safe convenient and effective treatment of vaginal candidasis.

Adhesives↗

Dissolution characteristics of megaloporous tablets prepared with two kinds of matrix granules.

The purpose of this study is to obtain a drug release at a constant rate with a megaloporous tablet, which was prepared with a simple formulation. These tablets were prepared with two kinds of granules. One of them is the restraining-phase matrix granule (RMG) and it controls the release rate of the drug. The other one is the soluble housing-phase matrix granule (HMG) and controls liquid penetration into the system. Eudragit RL 100 and Eudragit L 100 polymers were used to constitute the restraining and housing matrix phases, respectively. The effect of the amount of Eudragit RL 100 in the RMG was investigated and decreasing of amount of Eudragit RL 100 in the RMG increased the drug release rate. The tablets were prepared with compaction pressures of 188, 377, 1884 and 7540 kg/cm(2) and it was observed that the compaction forces ranging from 377 to 7540 kg/cm(2) did not influence drug release. The effect of the size of the matrices was demonstrated and it was found that the drug release rate increased with decreasing of the size of the tablets. The impact of the dosage to the dissolution rates was also investigated using two different amounts of drug. Therefore, the tablets were designed with two different dosages to use once or twice a day at the dosage interval of every 12 or 24 h, respectively. The release kinetic of the best formulation (4K) of the study was evaluated with the goodness-of-fit analysis and it was seen that the target profile was nearly achieved. This study suggests using megaloporous tablets in therapy, which could be prepared with a simple and cheap way similarly to conventional tablets to obtain a constant drug release.

Anti-Inflammatory Agents, Non-Steroidal↗

Matrix tablets based on thiolated poly(acrylic acid): pH-dependent variation in disintegration and mucoadhesion.

This study examined the influence of the pH on the mucoadhesive and cohesive properties of polyarcylic acid (PAA) and thiolated PAA. The pH of PAA (molecular mass: 450 kDa) and of a corresponding PAA-cysteine conjugate was adjusted to 3, 4, 5, 6, 7 and 8. The amount of immobilised thiol groups and disulfide bonds was determined via Ellman's reagent. Tablets were compressed out of each pH-batch of both thiolated and unmodified PAA and the swelling behaviour, the disintegration time and the mucoadhesiveness were evaluated. The amount of thiol/disulfide groups per gram thiolated PAA of pH 3 and pH 8 was determined to be 332 +/- 94 micromol and 162 +/- 46 micromol, respectively. The thiolated PAA tablets displayed a minimum four-fold higher water uptake compared to unmodified PAA tablets. A faster and higher water uptake of both polymer types was observed above pH 5. Thiolated polymer tablets showed a 3-20-fold more prolonged disintegration time than unmodified PAA tablets. The cohesiveness of PAA-cysteine conjugate increased at higher pH, whereas the unmodified PAA behaved inversely. A 3-7-fold stronger mucoadhesiveness was observed for the PAA-cysteine conjugate tablets compared to unmodified PAA tablets. For both thiolated and unmodified polymer the mucoadhesiveness was 2-4-fold enhanced below pH 5. The difference in mucoadhesion between the two polymer types was most pronounced at these lower pH values. In this study substantial information regarding the pH-dependence of mucoadhesion and cohesion of unmodified polyacrylates and of thiolated polyacrylates is provided, representing helpful basic information for an ameliorated deployment of these polymers.

Acrylic Resins↗